github.com/cockroachdb/tools@v0.0.0-20230222021103-a6d27438930d/go/analysis/passes/shadow/testdata/src/a/a.go (about)

     1  // Copyright 2013 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // This file contains tests for the shadowed variable checker.
     6  // Some of these errors are caught by the compiler (shadowed return parameters for example)
     7  // but are nonetheless useful tests.
     8  
     9  package a
    10  
    11  import "os"
    12  
    13  func ShadowRead(f *os.File, buf []byte) (err error) {
    14  	var x int
    15  	if f != nil {
    16  		err := 3 // OK - different type.
    17  		_ = err
    18  	}
    19  	if f != nil {
    20  		_, err := f.Read(buf) // want "declaration of .err. shadows declaration at line 13"
    21  		if err != nil {
    22  			return err
    23  		}
    24  		i := 3 // OK
    25  		_ = i
    26  	}
    27  	if f != nil {
    28  		x := one()               // want "declaration of .x. shadows declaration at line 14"
    29  		var _, err = f.Read(buf) // want "declaration of .err. shadows declaration at line 13"
    30  		if x == 1 && err != nil {
    31  			return err
    32  		}
    33  	}
    34  	for i := 0; i < 10; i++ {
    35  		i := i // OK: obviously intentional idiomatic redeclaration
    36  		go func() {
    37  			println(i)
    38  		}()
    39  	}
    40  	var shadowTemp interface{}
    41  	switch shadowTemp := shadowTemp.(type) { // OK: obviously intentional idiomatic redeclaration
    42  	case int:
    43  		println("OK")
    44  		_ = shadowTemp
    45  	}
    46  	if shadowTemp := shadowTemp; true { // OK: obviously intentional idiomatic redeclaration
    47  		var f *os.File // OK because f is not mentioned later in the function.
    48  		// The declaration of x is a shadow because x is mentioned below.
    49  		var x int // want "declaration of .x. shadows declaration at line 14"
    50  		_, _, _ = x, f, shadowTemp
    51  	}
    52  	// Use a couple of variables to trigger shadowing errors.
    53  	_, _ = err, x
    54  	return
    55  }
    56  
    57  func one() int {
    58  	return 1
    59  }
    60  
    61  // Must not complain with an internal error for the
    62  // implicitly declared type switch variable v.
    63  func issue26725(x interface{}) int {
    64  	switch v := x.(type) {
    65  	case int, int32:
    66  		if v, ok := x.(int); ok {
    67  			return v
    68  		}
    69  	case int64:
    70  		return int(v)
    71  	}
    72  	return 0
    73  }
    74  
    75  // Verify that implicitly declared variables from
    76  // type switches are considered in shadowing analysis.
    77  func shadowTypeSwitch(a interface{}) {
    78  	switch t := a.(type) {
    79  	case int:
    80  		{
    81  			t := 0 // want "declaration of .t. shadows declaration at line 78"
    82  			_ = t
    83  		}
    84  		_ = t
    85  	case uint:
    86  		{
    87  			t := uint(0) // OK because t is not mentioned later in this function
    88  			_ = t
    89  		}
    90  	}
    91  }
    92  
    93  func shadowBlock() {
    94  	var a int
    95  	{
    96  		var a = 3 // want "declaration of .a. shadows declaration at line 94"
    97  		_ = a
    98  	}
    99  	_ = a
   100  }